1. Field of the Invention
The present invention relates to a heat resistant structure which is used in a high temperature environment, particularly to a heat resistant structure of a honeycomb type in which a corrugated steel sheet and a flat steel sheet for a matrix to carry catalyst material are alternately joined by the use of a brazing material. The structure is used, for example, in a catalytic converter to purify exhaust gases from an automobile engine, whereby the catalyst is deposited or carried on the matrix of the structure.
2. Prior Art
As a heat resistant structure of a honeycomb type, it is known hitherto that a corrugated steel sheet and a flat steel sheet, each having the same thickness for a carrier matrix, are alternately laminated to each other, and joined with brazing material into a wound shape or vertically laminated into a multilayer block shape.
In such a conventional heat resistant structure, the brazing material is applied to the whole surface of contact between the corrugated and flat sheets which are alternately laminated to each other. In other words, the entire surface of the mutually contacted portions of brazing. Since the corrugated and flat sheets have different thermal expansion coefficients, it is difficult for the structure to absorb thermal expansion without straining or cracking, when the structure is used in a high temperature environment, and these structures consequently have poor durability.
Therefore, a technical method has been developed whereby corrugated and flat sheets of the same thickness are partially joined. For example, a heat resistant structure in which the corrugated and flat sheets are alternately laminated to each other are partially joined whereby brazing material is used for the joining. Since the corrugated and the flat sheets are partially joined, it is relatively easy to absorb thermal expansion, and the occurrence of strain or cracks is avoided.
In such a heat resistant structure, a plurality of pieces of brazing material of elongated belt shape are generally used, to simplify the interposing work or setting work, whereby a plurality of long pieces of brazing material are interposed at predetermined intervals of the width direction of the matrix along the longitudinal direction between the corrugated and flat sheets. FIG. 1 is an enlarged cross sectional view showing the main section of such a conventional heat resistant structure as the prior art. As shown in the drawing, brazing material A having the same width is hitherto used and are interposed at least at both edge portions of a matrix. There, a pair of brazing pieces A which face each other across the flat sheet 1 of the matrix are matched with respect to their counterpart in the width direction of the matrix.